Excavating equipment used in mining, construction, and a myriad of other ground engaging operations, typically includes a series of spaced apart ground engaging teeth mounted in side-by-side relation across a bucket lip. The teeth project forwardly to engage and break up the material to be gathered in the bucket. The art recognized long ago the advantages to be obtained by connecting the relatively small digging or excavating tooth to a relatively large adapter or support which, in turn, is connected to the bucket or excavating equipment. Typically, the adapter or support includes a base portion configured for attachment to the forward lip of a bucket and a free ended nose portion. In many applications, the conjuncture between the digging tooth and adapter involves providing the digging or excavating tooth with a pocket or cavity which opens to the rear of the tooth and fits over and along a substantial length of the nose portion of the adapter. A suitable pin operably interconnects the tooth and adapter in operable relationship relative to each other.
Typically, and especially in today's global economy, the components comprising a ground engaging multipiece tooth assembly are manufactured and/or fabricated in various global locations. That is, a digging tooth or tip can be manufactured or fabricated in one part of the world, i.e., China while the adapter or support for the tooth can be independently manufactured or fabricated in another part of the world, i.e., Mexico. It is common for these separate parts or components of the digging tooth assembly to be brought together only where the machine or apparatus on which they are to be arranged in manufactured and assembled. Accordingly, the parts or components of the multipiece tooth assembly require liberal tolerances to enable the parts fabricated at various global manufacturing facilities to fit and operate in combination relative to each other.
As will be appreciated by those skilled in the art, when connected to a bucket or the like, excavating tooth assemblies are often subject to highly abrasive conditions and, thus, experience rapid and considerable wear. Moreover, the relative high forces developed during operation of the excavating tooth assembly furthermore add to the rapid wear of the component parts of the excavating tooth assembly. Typically, each digging tooth is provided with a cutting edge extending across a forward edge of the tooth to facilitate penetration and breakup of the ground. The cutting edge of each tooth is oriented to extend transversely of the tooth and in generally parallel relationship with the work surface being excavated or dug.
In service, and although specific steps may have been applied to the tooth during its fabrication, the forward cutting edge of the tooth wears and quickly becomes dull and inefficient in the digging operation and, thus, require replacement. The multipiece construction of a tooth assembly advantageously allows the digging or excavating tooth of the assembly to be replaced independent of the adapter. Depending upon the type of excavation involved, a given adapter can be successively equipped with anywhere from five to thirty replacement teeth to maintain sharp penetrating edges. In the field, replacement of worn excavating tooth parts is a common and sometimes daily experience.
As can be appreciated, during an excavating, digging or loading operation extremely high vertical forces are imparted to each excavating tooth assembly associated with the excavating equipment. A conventional adapter or support has generally flat top and bottom surfaces upon which corresponding flat surfaces of the digging tooth bear upon. Under extreme loading conditions, and although interconnected through a pin or the like, the digging or excavating tooth tends to move forwardly and downwardly relative to the nose portion of the adapter. The loose fit between the component parts furthermore adds to relative movement between the tooth and adapter or support. The tendency of the tooth to move relative to the adapter exacerbates the wear problem especially in the pocket area and along the nose portion of the adapter. The existence of dust and dirt between the sliding confronting suifaces on the digging tooth and adapter furthermore adds to the deterioration of the component parts of the excavating tooth assembly. Thus, the critical conjuncture between the digging tooth and adapter is subject to accelerated wear conditions which can result in tooth pocket failure and/or premature adapter replacement.
While the vertical loads imparted to each tooth assembly during a ground engaging operation are significant, the horizontal or lateral loading imparted to the teeth are also of concern. For example, and as will be appreciated, the horizontal loads and forces imparted to a digging tooth affixed to a ripper and the like ground engaging equipment can be significant. Accordingly, each digging tooth assembly needs to be configured to accommodate both horizontal and vertical loads imparted thereto during normal operation. Of course, if the excavating tooth should break during operation, intermingling of a broken tooth component with the remainder of the excavated materials can cause significant material handling problems in subsequent operations, i.e., crushing operations. If a tooth or point is lost, the adapter quickly will become damaged as the nose portion of the adapter is not made to resist highly abrasive conditions. Moreover, and especially when considering excavator buckets or loaders, the horizontal width of each tooth assembly needs to be controlled in order to accommodate an adequate number of teeth along a forward edge or lip of the excavating equipment or bucket.
The securement of the excavating or digging tooth to the adapter requires a compromise between two opposing demands. On the one hand, the method of securing the tooth to the adapter must be strong enough to maintain the tooth and adapter in operable relationship notwithstanding the tremendous shock loads encountered during an excavating operation. Yet, when replacement of the tooth is required or desired, the pin for securing the tooth to the adapter must be readily removable. Often times, and especially in field conditions, removal/replacement of the retaining pin is accomplished under rather primitive conditions. Typically, the retaining pin has to be removed with only a hammer and drift pin which makes it difficult to overcome a tightly held locking engagement.
Heretofore, known pinning systems for securing an excavating tooth to an adapter have involved inserting a pin or multiple shorter pins either horizontally or vertically through openings in the tooth and adapter. Vertically oriented pin systems advantageously provide enhanced access to the pin. While providing enhanced access for striking the retaining pin with a hammer, the vertical orientation of the retaining pin exposes the retaining pin to rock and other media being excavated causing pin wear and, in some extreme cases, dislodgement of the retaining pin. Moreover, with vertical pin retention systems, the vertical movements of the excavating equipment tend to work against the vertically oriented pin system causing it to wear and, in some extreme cases, to become dislodged thereby allowing the tooth and adapter to become inadvertently separated during an excavating operation.
Horizontal pinning systems, while allowing for secure attachment of the digging tooth and adapter, also have certain drawbacks associated therewith. As will be appreciated, when secured across a front edge or lip of excavating equipment, the lateral or horizontal spacing between adjacent digging tooth assemblies and/or wear shrouds is minimized. Such tight space constraints make it difficult to horizontally drive a horizontally disposed retaining pin during installation and removal of the digging teeth. In fact, separate industries specifically directed to the problem of driving horizontal retaining pins relative to the digging tooth assembly are known and special devices have been proposed to address the problems inherent with horizontal pinning systems.
Thus, there is a need and a desire for a digging tooth assembly offering enhanced strength characteristics capable of handling extreme loading conditions imparted to the tooth assembly during a excavating operations and whose configuration lends itself to a pinning system which avoids the problems and difficulties associated with heretofore known horizontal and vertical pinning systems.